Aurora is about 3.5 times bigger than San Francisco.

San Francisco (including the city proper only) is approximately 121 sq km, while Aurora (map shows its 53 named neighbourhoods; the area covers the whole city) is approximately 425 sq km, making Aurora 251% larger than San Francisco.
Tip: This to-scale comparison of San Francisco vs. Aurora uses the Mercator projection, which distorts the size of regions near the poles.
Our free app, MapSize by MyLifeElsewhere — compare any two places, to scale on your mobile device.